Rightfielder Kyle Tucker left in the third inning of Houston's 7-4 win after fouling a ball off his right shin.
Tucker dropped to his hands and knees after the ball bounced off his leg, just below the knee. He remained in that position for several minutes while a trainer and manager, Joe Espada, checked on him.
He slowly got to his feet and took a few steps toward first base, where he appeared limping. He put his batting helmet back on but soon decided he couldn't continue his at-bat. He was replaced by pinch-hitter Mauricio Dubón.
The Astros officially considered Tucker, who's tied for second in baseball's home run race at 19, day-to-day.
Tucker said after the game that he was OK.
"We did some X-rays, and nothing was broken or anything," he said. "So I'm sure we'll do some more stuff (Tuesday) and whatnot. Right now, it's just kind of hurting, but it's all right; we'll get through it."
The Astros' injuries throughout the lineup are well-documented this season, where Houston enters Tuesday at 27-34 and third in the American League West.
On Tuesday night, Dubón is playing in place of Tucker in right field for the second of three games against St. Louis.
The Associated Press contributed to this report.
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